2017 Summary of Eastern Equine 

Encephalitis Cases in the United States

January 1 – December 31, 2017

This report is a descriptive summary of U.S. Eastern equine encephalitis (EEE) cases reported to the 

United States Department of Agriculture (USDA) in 2017. The USDA Animal and Plant Health Inspection 

Service (APHIS) Veterinary Services (VS) branch collaborates with the U.S. Centers for Disease Control 

and Prevention (CDC) and State veterinary and public health officials to facilitate communication about 

arbovirus disease cases in horses and confirm equine cases in each State. CDC collects arbovirus case 

information using its ArboNET reporting system, an electronic surveillance and reporting system used to 

track and report arboviral activity in humans and animals. During the transmission season, VS 

disseminates the equine arbovirus case information to State animal health officials for confirmation and 

posts the number of confirmed cases to the USDA equine infectious anemia disease information Web

site (http://www.aphis.usda.gov/animal-health/equine-health). This site also provides specific case 

definitions. In this document, ‘reported cases’ of EEE may include presumptive positive and confirmed 

positive cases. 

In 2017, 86 equine cases of EEE were reported from 13 States. Figure 1 shows the annual number of 

equine EEE cases reported in the U.S. from 2004 through 2017. Figure 2 shows the number of equine 

EEE cases in each State in 2016, and Table 1 provides the number of cases per county or parish in those 

States in 2017. 

Figure 1. Reported U.S. equine cases of Eastern equine encephalitis, 2004-2017

133

330

111

206

185

301

247

60

209

192

136

70

116

86

0

50

100

150

200

250

300

350

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Equine Cases of EEE

EEE Cases

Animal and Plant 

Health Inspection 

Service

Veterinary 

Services

March 2018
2017 Summary of Eastern Equine Encephalitis Cases in the United States

USDA-APHIS-VS 2

Figure 2. Distribution of reported equine EEE cases in 2017 (86 total cases) 

Table 1. Number of reported equine EEE cases by State and county, 2017

State County Eastern Equine Encephalitis Reported Cases

Alabama Baldwin County 1

Washington County 1

Total cases for Alabama 2

Arkansas Ouachita County 1

Pulaski County 1

Total cases for Arkansas 2

Florida Clay County 1

Franklin County 1

Jackson County 1

Levy County 1

Okaloosa County 1

Santa Rosa County 1
2017 Summary of Eastern Equine Encephalitis Cases in the United States

USDA-APHIS-VS 3

State County Eastern Equine Encephalitis Reported Cases

Total cases for Florida 6

Georgia Brooks County 1

Bryan County 1

Camden County 1

Echols County 1

Effingham County 1

Houston County 1

Lowndes County 1

Total cases for Georgia 7

Louisiana Iberville Parish 2

Lafourche Parish 1

Livingston Parish 1

Morehouse Parish 1

Total cases for Louisiana 5

Michigan Clare County 2

Marquette County 2

Menominee County 1

Roscommon County 1

Wexford County 1

Total cases for Michigan 7

Mississippi Attala County 1

Copiah County 1

Greene County 1

Jackson County 3

Newton County 1

Tate County 1

Wayne County 1

Total cases for Mississippi 9

North 

Carolina Bladen County 1

Cabarrus County 1

Camden County 1

Onslow County 1

Sampson County 2

Total cases for North Carolina 6

New Jersey Atlantic County 1

Cape May County 2

Cumberland County 2

Gloucester County 1
2017 Summary of Eastern Equine Encephalitis Cases in the United States

USDA-APHIS-VS 4

State County Eastern Equine Encephalitis Reported Cases

Total cases for New Jersey 6

Ohio Ashtabula County 1

Total cases for Ohio 1

South 

Carolina Aiken County 1

Charleston County 2

Chesterfield County 1

Dillon County 1

Horry County 2

Jasper County 1

Richland County 1

Total cases for South Carolina 9

Texas Hardin County 1

Jefferson County 1

Total cases for Texas 2

Wisconsin Chippewa County 3

Clark County 1

Jackson County 2

Juneau County 3

Marathon County 2

Monroe County 7

Price County 2

Shawano County 1

Taylor County 2

Trempealeau County 1

Total cases for Wisconsin 24

Total Reported Eastern Equine Encephalitis Cases for 

the United States 86